New conduction wires that can be stretched up to eight times their original length and used in headphones and phone chargers have been developed.

Scientists from North Carolina State University started with a thin tube made of an extremely elastic polymer and then filled the tube with a liquid metal alloy of gallium and indium, which is an efficient conductor of electricity.

"Previous efforts to create stretchable wires focus on embedding metals or other electrical conductors in elastic polymers, but that creates a trade-off," said Dr Michael Dickey, assistant professor and co-author of the study.

"Increasing the amount of metal improves the conductivity of the composite, but diminishes its elasticity," Dickey said.

"Our approach keeps the materials separate, so you have maximum conductivity without impairing elasticity. In short, our wires are orders of magnitude more stretchable than the most conductive wires, and at least an order of magnitude more conductive than the most stretchable wires currently in the literature," said Dickey in a statement.

While the manufacturing of the new wires is relatively straightforward, Dickey notes that one challenge needs to be addressed before the wires can be considered for popular products: how to minimise leakage of the metal if the wires are severed.